In addition to neutralization, antibodies (Abs) represent a critical bridge between the adaptive and innate immune system, as they mediate their activity by harnessing and instructing the innate immune system on how to clear the antigen to which they are bound. The ability of Abs to provide specificity to the innate immune system is tightly regulated by: a) the isotype of the antibody (Ab), and b) the glycan structure attached at the asparagine 297 within the CH2-domain of the Ab heavy chain. While Ab engineering has revolutionized the efficacy of monoclonal Abs through the optimization of Ab glycan structures for the treatment of malignancies and autoimmune disorders, little is known about how Ab glycosylation may be harnessed in vivo through vaccination to provide enhanced protection against infectious diseases. Accumulating evidence suggests that natural modulation of the Ab-glycan occurs under inflammatory conditions, dramatically altering the activity of an Ab. However, little is known about the mechanism(s) that regulates Ab-glycosylation, how the immune system naturally exploits this humoral activity, and how it may be harnessed to potentiate Ab-antiviral activity. Given that innate immune recruiting Abs are detectable in early HIV infection, are enriched in long-term non-progressors, and correlate with enhanced HIV control, the PI hypothesizes that the rules for eliciting innate immune recruiting Abs, with specific glycans in vivo, can be learned from natural infection. Thus in this proposal, the PI will hone in on the B cell biology of glycosylation to define a) the mechanism by which Ab-glycosylation is tuned naturally in spontaneous controllers, b) define the mechanism by which glycosylation in B cells is regulated, and c) determine whether Ab-glycosylation is remembered following immunization. Together, knowledge gained from these studies will provide critical insights into the mechanism by which Ab-effector functions are regulated, and will lead to the generation of new strategies to potentiate the antiviral activity of vaccine inducd Abs. PUBLIC HEALTH RELEVANCE: This proposal aims to define the mechanism(s) regulating antibody glycosylation in B cells. These studies may identify new strategies to specifically tune B cell responses during vaccination to induce antibodies with enhanced antiviral activity.